Filter实现全站页面Gzip压缩输出

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package cn.xingkong.filter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class GzipFilter implements Filter {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        MyResponse myres = new MyResponse(response);
        chain.doFilter(request, myres);
        byte[] data = myres.getBuffer();
        byte[] result = gzip(data);
        response.setHeader("content-encoding", "gzip");
        response.setHeader("content-lenght", result.length + "");
        response.getOutputStream().write(result);
    }

    public byte[] gzip(byte[] b) throws IOException {
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        GZIPOutputStream gout = new GZIPOutputStream(bout);
        gout.write(b);
        gout.close();
        return bout.toByteArray();
    }

    class MyResponse extends HttpServletResponseWrapper {
        private ByteArrayOutputStream bout = new ByteArrayOutputStream();
        HttpServletResponse response;
        private PrintWriter pw;

        public MyResponse(HttpServletResponse response) {
            super(response);
            this.response = response;
        }

        @Override
        public ServletOutputStream getOutputStream() throws IOException {
            return new MyServletOutputStream(bout);
        }

        @Override
        public PrintWriter getWriter() throws IOException {
            // TODO Auto-generated method stub
            pw = new PrintWriter(new OutputStreamWriter(bout,
                    response.getCharacterEncoding()));
            return pw;
        }

        public byte[] getBuffer() {
            if (pw != null) {
                pw.close();
            }
            return bout.toByteArray();
        }

    }

    class MyServletOutputStream extends ServletOutputStream {
        private ByteArrayOutputStream bout;

        public MyServletOutputStream(ByteArrayOutputStream out) {
            this.bout = out;
        }

        @Override
        public void write(int arg0) throws IOException {
            bout.write(arg0);
        }

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}

web.xml配置

<filter>
    <filter-name>GzipFilter</filter-name>
    <filter-class>cn.xingkong.filter.GzipFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>GzipFilter</filter-name>
    <url-pattern>*.jsp</url-pattern>
    <dispatcher>FORWARD</dispatcher>
    <dispatcher>REQUEST</dispatcher>
  </filter-mapping>


  <filter-mapping>
    <filter-name>GzipFilter</filter-name>
    <url-pattern>*.html</url-pattern>
  </filter-mapping>


  <filter-mapping>
    <filter-name>GzipFilter</filter-name>
    <url-pattern>*.js</url-pattern>
  </filter-mapping>